Harmonic piezodrive - miniaturized servo motor

Miniaturised dc-motors used in servomotor applications show some disadvantages like very high speed and therefore are combined with gearsets of a high gear ratio which introduce backlash and low efficiency. This article proposed a different kind of motor principle by the combination of a harmonic drive gearbox and stack piezoactuators. The actuators replace the functionality of the wave generator generating a travelling wave into the flexspline element of the gearbox. After some theoretical conclusions for control and torque calculations the functionality of the new motor principle is proven by a prototype.